Patient with cancer commonly experience pain due to the cancer itself, the cancer treatment, or a combination of both.
Pain is a complex symptom that affects most aspects of a person’s life, including physical functioning, the performance of activities of daily living, psychological and emotional status, and social interactions. The prevalence of pain among cancer patients varies widely and is influenced by numerous factors, including the specific type of cancer and its extent, and the treatment setting. Virtually all patients with malignant disease experience recurrent episodes of acute pain, which may accompany surgery, invasive procedures, or complications, such as pathological fracture. The estimated prevalence of chronic pain in populations undergoing cancer treatment ranges from 33 to 59 percent, and it is considerably higher (64 to 74 percent) in patients with advanced disease [1,2].
Tissue injury produced by the neoplasm is the primary etiology in about three-fourths of patients with chronic cancer pain, and the remainder have pain related to the late effects of antineoplastic therapy or to painful comorbidities. How much pain the patient experiences is not necessarily related to the growth of the cancer: a very slow tumour pressing on a nerve can be extremly painful, while a very large tumour somewhere else might not cause any pain at all.
The bones of the axial skeleton are the predominant site of metastasis in most men with metastatic prostate cancer, and these lesions can cause pain, debility, and/or functional impairment. The bone metastases in men with prostate cancer are usually osteoblastic (ie, characterized by new bone formation). However, increases in bone resorption have been consistently demonstrated histologically and biochemically. Bone destruction is an important factor in the etiology of pain and other complications due to bone metastases, although it is unclear if such bone destruction precedes the development of osteoblastic metastases or is a consequence of increased bone formation.
Adequate pain relief can be achieved in 70 to 90 percent of patients when well accepted treatment guidelines for cancer pain are followed. [3,6].
Uncontrolled pain results in unnecessary suffering, decreased ability to cope with illness, interference with activities of daily living, and extended or repeat hospital admissions. Uncotrolled pain may also delay or disrupt anticancer treatment, compromising its effectiveness.
Assessment of cancer pain
Cancer pain is routinely assessed as an integral part of cancer care. Pain is a subjective and multidimensional experience. Cancer pain evaluation begins with a thorough history of both the pain and the underlying malignancy as well as their treatment. The pain report should include: intensity, temporal features, location and patterns of radiation, quality, and factors that provoke or relieve the pain. Because of the potential impact of pain on quality of life, it is also essential to determine the adverse effects of pain on physical and psychosocial wellbeing, as well as the spiritual impact of the pain.
Pain intensity is often measured simply by using a verbal rating scale (eg, “mild,” “moderate,” or “severe”) or a numeric scale (eg, “How severe has your pain been, on average, during the past week, last 24 hours, on a scale of 0 to 10, where 0 is no pain and 10 is the worst pain you can imagine?”).
Cancer pain should be regularly reassessed to ensure it is managed effectively.
There are many ways to manage different types of cancer-related pain. The pain relief offered depends upon the type and severity of the pain, as well as the patient´s general health and level of fitness. Patient should be fully informed and involved in decision about treatment options.
Treatment options for cancer pain include non-opiod analgesic drugs, opioids, adjuvant drugs, radiotherapy and in some cases, surgery.
Fig. 1 Analgesic Ladder Adapted from: Martuliak I. Via pract, 2005; 2(6):296-301
Patients with cancer pain that is generally mild should first be treated with paracetamol or a non-steroidal antiinflammatory drug (NSAID, e.g. metamizole, ibuprofen, diclofenac). This Step 1 of the ladder also states that this analgesic may be combined with an adjuvant drug that provides additional analgesia (ie, a so-called “adjuvant analgesic,” such as an analgesic antidepressant drug for neuropathic pain), treats a side effect, or manages a coexisting symptom.
Patients with moderate to severe pain, and those with chronic pain that is less intense but does not respond adequately to a trial of an NSAID alone, should be treated with an opioid (pain relievers available legally by prescription).
The analgesic ladder promotes the concept that one group of opioids should be conventionally used to treat pain of moderate intensity (step 2 of the ladder) and the other group of opioids should be conventionally selected for severe pain (step 3 of the ladder). On both steps 2 and 3, the approach indicates the potential for benefit with combination therapy that includes an NSAID or other drugs to enhance analgesia or treat side effects.
Opioids act by binding to specific receptors, which are present in tissues throughout the body, including both the peripheral and central nervous systems. Opioids, which are available only by prescription, are used quite often due to multiple routes of administration, ease of titration and effectiveness for all types of pain (ie, somatic, visceral, neuropathic).
Cancer-related bone pain caused by bone metastases can be treated with radiotherapy, bisphosphonates and biologic drug (human monoclonal antibody), which reduces bone resorption, increases bone density, and reduces bone fractures. Bisphosphonates are not considered pain medications as such, but can delay the onset of bone pain and prevent bone complications such
as fractures. Percutaneous vertebroplasty can also reduce spinal pain by stabilising the bones.
In selected patients with multiple bone metastases, radioisotope therapy using strontium, samarium or rhenium can be effective in achieving pain relief in multiple sites. More innovative bone-targeted radiopharmaceutical, alpha-radionuclide, has also shown benefit in overall survival prolongation . Radioisotope therapy is a procedure in which a liquid form of radiation is administered internally through infusion or injection. Its ultimate purpose is to treat cancerous cells with minimal damage to the normal surrounding tissue.
Pain from spinal cord compression caused by metastases is typically treated with radiotherapy with or without steroids, and occasionally with surgery to remove the tumour or stabilise the vertebrae.
Neuropatic pain can be caused by the cancer itself, cancer therapies or infections (such as herpes zoster). It causes unpleasant sensations and can be difficult to treat. Neuropathic pain in patients with cancer is treated with opiods as well as adjuvant drugs that can reduce nerve pain, including anticonvulsants, antidepressants and lidocaine patches.
Breakthrough cancer pain is defined as a transitory flare of pain that occurs on a background of relatively well-controlled baseline pain. Typical episodes of breakthrough cancer pain are of moderate to severe intensity, rapid in onset (minutes) and of relatively short duration (median 30 minutes) and are typically treated with fast-acting opiods.
Refractory pain (persistent pain that is not relieved by standard drug treatment) may rarely require more invasive strategies, such as intrathecal opiod treatment (therapy via implantable infusion pump systems into a spinal canal), peripheral nerve block, neurolytic blockade (a form of nerve block by the application of chemicals), spinal cord stimulation or cordothomy (surgical procedure that disables selected pain-conducting tracts in the spinal cord).
Possible side effects of treatment for cancer pain
The side effects from cancer pain treatments are usually mild. Common side effects of NSAIDs include effects on the gastrointestinal system, skin rash or itching. The common side effects of opioid analgesics include bowel dysfunction (e.g. constipation, bloating, incomplete evacuation, increased gastric reflux), nausea, vomiting, pruritus, respiratory depression and central nervous system toxicities (drowsiness, cognitive impairment, confusion, hallucinations, myoclonic jerks and rarely, opioid-induced hyperalgesia). Hydratation may be necessary to ensure that by-products of opioids pass through the kidneys without causing problems. Many of the side effects of opioids can be managed by reducing the dose of the opioid, switching to a different opioid or using specifing additional drugs to treat the side effect.
Psychologists or specialist counsellors can help patients and their families to deal with the emotional challenges associated with cancer and cancer-related pain.
Local, national and international patient support groups are available for specific types of cancer. These groups can provide help for patients to better understand their disease, allow them to share their experiences with others, and help them to learn how to cope with cancer.
MUDr. Jana Obertová, Ph.D.
Národní onkologický ústav, Bratislava
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- Fallon, R. Giusti, F. Aielli, P. Hoskin, R. Rolke, M. Sharma & C. I. Ripamonti, on behalf of the ESMO Guidelines Committee Management of Cancer Pain in Adult Patients: ESMO Clinical Practice Guidelines Ann Oncol (2018) 29 (Suppl 4): iv166–iv191
- Martuliak I. Neopioidové analgetiká v liečbe chronickej bolesti. Via pract., 2005, roč. 2 (6): 296–301.
- Parker C, Nilsson S, Heinrich D, et al. Alpha emitter radium-223 and survival in metastatic prostate cancer. N Engl J Med 2013; 369:213.
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